Method of constructing turning tables for electric furnaces



24, 195.4 T. ELLEFSEN 2,686,961

METHOD OF CONSTRUCTING TURNING TABLES FOR ELECTRIC FURNACES Filed Feb.8, 1952 2 Sheets-Sheet 1 INVENTOR. Ybrmzs [tie/sew ATTORNEYS Aug. 24,1954 T. ELLEFSEN METHOD OF CONSTRUCTING TURNING TABLES FOR ELECTRICFURNACES Filed Feb. 8, 1952 2 Sheets-Sheet 2 Patented Aug. 24, 1954METHOD OF CONSTRUCTING TURNING TABLES FOR ELECTRIC FURNACES TonnesEllefsen, Porsgrunn, Norway, assignor to Elektrokemisk A/S', acorporation of Norway Application February 8, 1952, Serial No. 270,730

3 Claims.

In United States Patent No. 2,300,355, dated October 27, 1942, I havedescribed an electric furnace in which relative movement between theelectrodes and the charge is preferably obtained by maintaining theelectrode stationary and rotating the body of the furnace. The presentinvention relates to a method of constructing such furnaces whereby theymay be operated efficiently with a relatively small expenditure ofpower.

As shown in my earlier patent the furnace body is mounted on wheelspositioned toward the circumference of the furnace, which wheels run ona track. Experience has shown that it is exceedingly diflicult toarrange these wheels so that they carry a uniform load. As a result,certain of the wheels have carried the major portion of the load and thefriction on these wheels has been so great that undue power consumptionhas been used to maintain the furnace in rotation. It will be realizedthat this problem is a serious one when it is borne in mind that thefurnace to be rotated may weigh from 200 tons to 500 tons.

In accordance with the present invention I build such a furnace asfollows:

First of all, a proper foundation is laid and on this is built a trackwhich is as level as possible.

This track is then machined for accuracy, preferably by a rotary cutterpivoted at its center. A central plate or member is then provided andradial arms run out from this central plate to which are attached thewheels that run on the track. These radial arms are of substantialstrength but are of sufficient flexibility relative to the centralmember so that the wheels will all rest evenly on the track during thetime that the concrete is being poured and hardened.

The actual shaping of the concrete mass is accomplished by providingforms supported from below onto which the concrete is poured. Theseforms support the central member to which the arms running out to thewheels are attached and these forms should be so arranged that theconcrete can embed the attachments to the wheels without imposing anymaterial weight on the wheels before the concrete has hardened. Sincethe wheels will be resting on the track throughout the whole periodwhile the concrete is being poured, it will be found that when theconcrete has hardened and the forms are removed, the weight of theconcrete support bed is evenly distributed between the wheels.

I find it preferable to provide the central plate with a thrust memberand to provide a corresponding thrust member on the foundationimmediately below. By having these two members spaced apart slightly,friction at this point will be avoided but nevertheless the supportswill be present as an emergency bearing in case anything should happento the wheels. If desired there may even be some contact and a smallpart of the load may be carried on this central support but thisordinarily is not advisable, as it is preferred that after the supporttable is cast and has become rigid, the entire weight should be carriedon the wheels and be distributed equally between them.

When the support table has hardened and is fully rigid, the actualfurnace is erected on this table and preferably is carried on columnseach of which is positioned at a point on the support table directlyover one of the rotating wheels. By this arrangement the furnace can berotated with a remarkably low expenditure of power.

This invention can readily be understood by reference to theaccompanying drawings which illustrate the production of a. furnace madein accordance with my invention. In these drawings Fig. 1 shows avertical section through a furnace embodying my invention; Fig. 2 showsa plan view of the furnace of Fig. 1 with parts broken away and Fig. 3shows a sectional view with the wheels and forms for pouring theconcrete support in place and the concrete mass of the support tableindicated.

In these drawings, [9 is the foundation for the furnace which must bevery solidly built so that it will remain fixed. On this furnace ismounted the track I 2 the top of which is machined to make it smooth andabsolutely level. In the middle, the foundation carries an upwardextension I4 on which is positioned a support member [6 which may be ofmetal. Another support member l3 preferably also of metal is positionedabove the support It. Each of these supports is preferably provided witha central opening and through them runs a central shaft 20 which may befixed in the support It; and rotate freely in support [8 or vice versa.The support member I S and shaft 20 may be used as a central tap forgrinding the track 12. Shaft 20 preferably is made hollow and may beemployed for running pipes for cooling water and the like to thefurnace.

The manner in which the support table for the furnace is poured or castis indicated in Fig. 3. As shown in this figure, temporary forms areprovided braced from below on the foundation In. In the particularembodiment here illustrated these forms are shown as made up of radialtimbers 22 carried by vertical struts 24. Short struts 26 support theinner ends of the beams 22 and if desired the beams 22 can have theirinner ends running beneath the upper flange of support member [8.

A series of wheels 28 rest on the track [2 and are connected with thesupport member 18 by the central plate or member 30 and the flexiblemetallic arms 32. The arms 32 are connected to the hub mounts 3 in whichthe hubs of the wheels 23 rotate. A flooring 36 is built on the beams 22to support the concrete table while it is hardening and the hub mounts34 of the wheels are free to move vertically relative to this flooringsufliciently so that the wheels 28 rest on the track 12 without carryingany appreciable part of the weight of the structure which is to supportthe concrete bed of the furnace. In the embodiment shown, the arms 32are shown as interconnected by circular plates 38, 40 and 42, andextending upwardly from these plates and also from plate 30, are bolts44 carrying crossbars 45 which will be firmly embedded in the finalconcrete. In addition to the flooring 3b the form includes side walls 48also supported from the beams 22.

When thi framework is erected as indicated in Fig. 3, it is to be notedthat each wheel rests evenly on the track l2 and since the arms 32 areflexible, there is no substantial pressure on these wheels to bring themout of adjustment.

A concrete slab is now poured on the platform 1 36 and within the sidewalls 43. The top shape of this slab is indicated in dot and dash linesin Fig. 3. This concrete slab will be entirely supported by the beams 22and the struts which hold these beams up, and virtually none of theweight of the concrete will be transmitted to thewheels 20 which willstill stay evenly pressed on the track l2.

Ultimately when the concrete has thoroughly set, the strutsZt and 2t andbeams 22 and the forms supported by these beams will be removed. Now theweight of the slab will be carried by the wheels 28but since thesewheels were at all times pressing'evenly on the track 82, they willcontinue to do so and thus an even distribution of weight on the wheelsis attained.

Subsequently, the columns 52 of brickwork or the like are built on theconcrete mass 59 and preferably these columns are positioned over eachwheel 28. Onthese columns is positioned the main furnace 54. The numeral56 indicates the electrodes which extend down into the furnace chamberbut are held stationary as explained in my earlier'patent.

The furnace can be rotated by means of an electric'motor 58 operatingthrough a gear train on the internal gear 68 which is attached to thearms 32 by means of projections on bolts Mi.

It is to be borne in mind that the furnace rotates very slowly. Forexample, it may make approximately one rotation in 24 hours. Bydistributing the weight evenly between the wheels 23 asdescribed I havefound it possible to drive afurnace weighing 2000 tons with a motor offrom to /2-horsepower.

It may also be noted that a wall 62 is supplied outside the wheels 28and the track l2. This should be of suflicient strength to carry thesupport table and protect the machinery against damage in the event ofwheel breakage. Also it will protect the rotating mechanism in case anyof the contents ofthe furnace should spill over.

It is understod that the foregoing specific example is given only forthe purpose of illustration,

This application is a continuation-in-part oil my earlier applicationSerial No. 729,961, filed February 20, 1947, now abandoned. i

What I claim is:

1. The method of constructing a rotatable furnace of great weight whichcomprises forming a level circular track, positioning on the track on afixed solidly built foundation a series of spaced wheels each providedwith a hub having an upwardly extending mount, interconnecting such hubmounts by a-metallic support structure sufficiently flexible so that thewheels will rest evenly on the track, providing a formsupportedindependently of the wheel hubs and their mounts below and around suchmetallic support structure but above said wheels into which concrete canbe poured, pouring concrete into such form while the wheels are restingevenly on the track to form a concrete slab in which the metallicsupport structure connecting the hub mounts is embedded, permitting suchconcrete slab to harden whereby the hub mounts of the wheels arepermanently locked in relative vertical position so that the wheels willbe free to rotate but will bear equally on the track, removing the formson which the concrete structure is cast so that the weight of the slabis carried on the wheels and constructing a furnace on such slab.

2. A method as specified in claim 1 in which the form for the concreteslab is adapted to support the central portion of such metallic supportstructure while the hub mounts oi the wheels are free to move verticallyrelative to such form sufficiently so that the wheels rest on the trackwithout carrying any appreciable partof the weight of such form.

3. A method as specified in claim 1 which further includes the step ofattaching to said metallic support structure, after the concrete slab inwhich it is embedded has hardened, a driving mechanism whereby said slabmay be rotated.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,309,384 Yeomans July 8, 1919 FOREIGN PATENTS Number CountryDate 921,027 France Jan. 8, 1947

